Hello, to all I'm new with much respect, I will give my thought on this topic I believe also OSAS, but, I will explain why.
As " the Holy Ghost teacheth; comparing spiritual things with spiritual " 1st Corinthians 2:13.
But he that received the seed into stony places, the same is he that heareth the word, and anon with joy receiveth it; Yet hath he not root in himself, but (en-) dureth for a while: for when tribulation or persecution ariseth because of the word, by and by he is offended. He also that received seed among the thorns is he that heareth the word; and the care of this world, and the deceitfulness of riches, choke the word, and he becometh unfruitful "
" Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works? And then will I profess unto them, I never knew you: depart from me, ye that work iniquity"
It is not that they were "once" saved , then lost their salvation but the Christ NEVER knew them as his own! Matthew 13:20-21 & 7:22-23
Concerning the phrase, "once saved ALWAYS saved". How long is Eternal? An indefinite duration of Time. Christ promises the True Born Again Child of God, " Verily, verily, (It's True, it's true) I say unto you, He that believeth on me hath Everlasting life. " John 6:47.
" My sheep hear my voice, and I know them, and they follow me: And I give unto them Eternal life; and they shall never perish, neither shall any man pluck them out of my hand" John 10:27-28.
" Neither by the blood of goats and calves, but by his own blood he entered in once into the holy place, having obtained Eternal redemption for us. For if the blood of bulls and of goats, and the ashes of an heifer sprinkling the unclean, sanctifieth to the purifying of the flesh: How much more shall the blood of Christ, who through the Eternal Spirit offered himself without spot to God, purge your conscience from dead works to serve the living God? " Hebrews 9:12-14.
Let no man deceive you by any means: for that day shall not come, except there come a falling away (Greek word - Apostasia- APOSTASY ) first, and that man of sin be revealed, the son of perdition " 2nd Thessalonians 2:3.
"They profess that they know God; but in works they deny him, being abominable, and disobedient, and unto every good work reprobate " Titus 1:16
Keyword being PROFESS